This disclosure relates generally to icemakers for household refrigerators and more particularly to such ice makers having an ejection arm that is extendable into the ice making cavity.
Refrigerators with ice makers are a popular consumer item, and most side-by-side refrigerator/freezers have icemakers installed as standard items or are wired to accommodate an add-on ice maker. In a typical refrigerator/freezer with an icemaker, water is introduced into ice forming compartments in an ice tray and allowed to freeze to form ice cubes.
Typically, water is allowed to flow into the ice tray until each of the compartments is filled to a desired level. The water is then allowed to stand in the tray until it freezes. The freezing point of pure water is commonly identified as 32 degrees Fahrenheit (0 degrees Celsius), but water purity, air pressure and other parameters can alter the freezing point. As the water in the cavity is cooling, it is possible for temperatures to vary in different portions of the water, i.e. the water in the ice forming compartments includes a temperature gradient or is otherwise not in an isothermal state.
Various factors contribute to the non-isothermal state of the water in the ice forming compartments. Typically prior to each ejection cycle, a heater heats the tray to induce the ice tray to expand to facilitate the ejection process. To induce this expansion the temperature of the tray must be increased often several degrees above freezing. After ejection of the ice, new fill water at a temperature above the freezing point is added to the tray. While the air temperature in the freezer compartment typically remains well below freezing throughout the ejection and refilling process, the temperature of the ice tray, as a result of heating with the heater and contact with the liquid water is at least initially above the freezing point of water during the beginning of an ice making cycle. As a result, a temperature gradient may be created in the water in the ice tray with the water adjacent the surface being colder than the water adjacent the tray. Thus, the surface of the water often freezes first.
Once the surface freezes, the surface ice acts as an insulation layer that buffers the temperature of the water adjacent thereto at or close to freezing. The tray however remains in contact with the air of the freezer compartment which is well below the freezing point of water. Thus, by convection cooling the water adjacent the tray begins to cool faster than the water adjacent the surface ice. Thus, the water adjacent or in contact with the tray freezes after the surface freezes and the center of the ice cube is typically the last part to freeze.
Water expands in the transition from liquid to solid. During the freezing and expansion of the water in the center of the ice cube, the walls of the tray act to stop expansion of the ice cube in the direction perpendicular to the compartment walls. Thus the only direction for expansion is perpendicular to the top surface of the ice adjacent the air of the freezer. Thus, a bulge is normally formed in the center of the top surface of the ice cube. This is caused by several factors as mentioned above. Also, because the sides of the cavity usually cool faster after a surface layer of ice is formed, ice will form adjacent the tray walls before forming in the center of the cube. Thus, the center of the ice cube will be the last part to freeze, and this is one of the causes of the bulging effect.
Additionally, once the top surface of the water in the ice forming compartments of the ice tray freezes, gasses are trapped below the solid surface of the ice. These trapped gasses can lead to cracking of the ice in the compartment or to cloudiness of the ice.
After freezing, an ejector arm rotates so that a separate finger or ejector member extends into each compartment to urge the ice formed therein to be ejected. After ejecting the ice, the ejector arm in typical ice makers returns to a position wherein each of the fingers is disposed completely outside of the compartment during the next filling, cooling and freezing cycles.
Consumers often equate cloudy ice with impurities or old ice. Thus, it would be desirable to produce clear ice. It would also be desirable to produce ice without a bulge on the top surface. Such desired results are facilitated by reducing the temperature variation in water in an ice forming compartment of an ice tray during the freezing process. Stirring ice during cooling and prior to freezing facilitates the production of clearer ice while reducing the bulge on the top surface.
According to one aspect of the disclosure, a method of making ice comprises an advancing water step, a reducing step, a stirring step, a moving step and an advancing the ejector member step. The advancing water step includes advancing water into at least one ice forming compartment of an ice tray. The reducing step includes reducing the temperature of the water within the at least one ice forming compartment. The stirring step includes stirring the water within the at least one ice forming compartment with an ejector member during the reducing step. The moving step includes moving the ejector member to a stop position after the stirring step at which the ejector member is spaced apart from the water located in the at least one ice forming compartment. The advancing step includes advancing the ejector member into contact with ice formed in the at least one ice forming compartment after the moving step so that the ice is urged out of the at least one ice forming compartment.
According to another aspect of the disclosure, an icemaker assembly, comprises an ice tray and an ice ejector. The ice tray has at least one ice forming compartment. The ice ejector has at least one ejector member. The ice ejector is operable to (i) stir water located within the at least one ice forming compartment with the at least one ejector member during a first mode, and (ii) urge ice out of the at least one ice forming compartment with the at least one ejector member during a second mode.
According to yet another aspect of the disclosure, a method of making ice comprises an operating an ice ejector of an icemaker in a first mode of operation step and an operating an ice ejector of an icemaker in a second mode of operation step. In the operating an ice ejector of an ice maker in a first mode of operation step, a plurality of ejector members of the ice ejector are respectively advanced through water located within a plurality of compartments of an ice tray of the ice maker during cooling of the water in the ice tray. In the operating the ice ejector in a second mode of operation step, the plurality of ejector members are respectively advanced into contact with ice formed within the plurality of ice forming compartments so that the ice is urged out of the plurality of ice forming compartments.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.
Corresponding reference characters indicate corresponding parts throughout the several views. Like reference characters tend to indicate like parts throughout the several views.